In [1]}, the authors studied the covert communications with a self-sustained relay over Rayleigh fading channels, where the relay harvests extra energy from the source to transmit covert message to destination by employing a more powerful energy harvester with a higher conversion efficiency factor, while the source is to detect the covert communication. The work aims to find the maximum throughout, given a certain level of covertness for two energy harvesting schemes, time switching and power splitting. Covert communication with a positive rate was shown to be possible in the transmission from a relay node to a destination when the source is uncertain regarding the forwarding strategy of the relay node.
